The present invention relates to a piston supporting structure for a linear compressor, and in particular to a piston supporting structure for a linear compressor in which a spring elastically supporting a piston supports the piston, being only axially contracted and relaxed by the reciprocating movement of the piston in receipt of driving force of a motor, While not being displaced in a radial direction.
Generally, a compressor constituting a refrigerating cycle apparatus compresses refrigerant introduced from an evaporator and discharges the same to a high temperature and pressure state.
A linear compressor, an example of the above-described compressor, inducts refrigerant gas and compresses the same by driving force of a motor transferred to a piston reciprocating in a cylinder. At this time, the piston is elastically:supported by springs at both sides thereof, and the kinetic energy thereof is stored.
As illustrated in FIG. 1, the above-described linear compressor includes a closed vessel 1 formed to have predetermined inner space, an inner case 2 installed at the inner center portion of the closed vessel 1 and formed to have a predetermined inner space, a cover plate 3 for covering and opening one side of the inner case 2, a cylinder 4 connected to the cover plate 3 so as to be positioned at the inner portion of the inner case 2, an outer lamination 5 connected to the inner side of the inner case 2, an inner lamination 6 connected to the cylinder at a predetermined distance from the outer lamination 5, a magnet 7 inserted between the inner lamination 5 and the outer lamination 6 thereby to construct a motor including them, a piston 8 connected to a cylindrical compression space (P) formed at the inner portion of the cylinder 4 to be reciprocatingly movable, a connecting member 9 formed in a predetermined shape with its one side being connected to the magnet 7 and the other side being connected to one side of the piston 8 for thereby transferring driving force of the motor to the piston 8, a cover 10 for covering and opening the other side of the inner case 2, an inner spring 11 connected between the connecting member 9 and the inner lamination 6, and an outer springs 12 connected between the connecting member 9 and the cover 10.
The inner spring 11 and the outer spring 12 are usually round coil springs.
In addition, a valve assembly 13 for inducting refrigerant gas into the cylinder 4 and discharging compressed refrigerant gas to the outside of the cylinder 4 and a head cover 14 are connected to one side of the cylinder 4.
Unexplained reference numerals 15 and 16 in FIG. 5 each represents a winding coil and an oil feeder.
Hereinafter, the operation of the conventional linear compressor thus constructed will now be described.
When a current is applied to the motor, the magnet 7 linearly reciprocates. The linear reciprocating movement of the magnet 7 is transferred to the piston by the connecting member 9, and thereby the piston 8 reciprocates in the compression space (P) of the cylinder.
In this manner, as the piston 8 reciprocates in the compression space (P) of the cylinder 4 refrigerant gas induced into the closed vessel 1 is inducted into the compression space (P) of the cylinder 4 through a refrigerant inlet passage (F), compressed and discharged to the outside of the cylinder through the valve assembly 13 and the head cover 14 repeatedly.
At this time, the piston 8 is elastically supported by the inner and outer springs 11 and 12 positioned at both sides of the piston 8, while storing and discharging kinetic energy. Hereinafter, the example of the piston supporting structure for the conventional linear compressor of the inner and outer springs 11 and 12 supporting the piston 8 will now be described.
As illustrated in FIG. 2, a first supporting plate 17 including a disc unit 17a having a predetermined thickness and a circumferential unit 17b vertically curved and extended to have an inner diameter corresponding to the outer diameter of the outer spring 12 at the circumferential portion of the disc unit 17a is connected to the inner side of the cover 10.
In addition, a second supporting plate 18 including a disc unit 18a having a predetermined thickness and a circumferential unit 18 vertically curved and extended to have an inner diameter larger than the outer diameter of the outer spring 12 at the circumferential portion of the disc unit 18a is connected to the outer side of the connecting member 9 so that it is opposed to the first supporting plate 17.
In addition, a third supporting plate 19 including a disc unit 19a having, a predetermined thickness and a circumferential unit 19b vertically curved and extended to have an inner diameter larger than the outer diameter of the inner spring 11 at the circumferential portion of the disc unit 19a is connected to the inner side of the connecting member.
In addition, a fourth supporting plate 20 including a disc unit 20a having a predetermined thickness and a circumferential unit 20b vertically curved and extended to have an inner diameter larger than the outer diameter of the inner spring 11 at the circumferential portion of the disc unit 20a is connected to the outer side of the inner lamination 6 so that it is opposed to the third supporting plate 19.
The outer spring 12 is connected between the first and second supporting plates 17 and 18 thus connected, and the inner spring 1 is connected between the third and fourth supporting plates 19 and 20.
In detail, one end portion of the outer spring 12 is fixedly connected to the first supporting plate 17, and the other end portion is loosely 20 supported by the second supporting plate 18.
In addition, one end portion of the inner spring 11 is loosely supported by the third supporting plate 19, and the other end portion is fixedly connected to the fourth supporting plate 20.
Therefore, when the piston 8 reciprocates by driving force of the motor transferred to the piston 8 by the connecting member 9, the outer spring 12 and the inner spring 11, as illustrated in FIG. 3, are positioned linearly in the axial direction, and then elastically support the movement of the piston 8 while repeatedly being contracted and relaxed and store and discharge kinetic energy into elastic energy at the same time.
FIG. 3 and FIG. 4 to be explained below illustrate only the operation of the inner spring 11.
However, in the conventional linear motor described above, when the inner and outer springs 11 and 12 for elastically supporting the piston reciprocating in the compression space (P) of the cylinder in receipt of driving force of the motor by the connecting member 9 are contracted and relaxed in the axial direction, the inner and outer springs 11 and 12 each supported by the second supporting plate 18 and the third supporting plate 19 connected to the connecting member 9 connected to the piston 8 are loosely supported. Therefore, as illustrated in FIG. 4, when the inner and outer springs 11 and 12 are contracted and relaxed in the axial direction, an eccentricity is generated in a radius direction. Then, as illustrated in FIG. 5, an angular moment due to F3 and Fb which are in the reciprocal directions is applied to the piston 8 by the eccentricity of the spring. Subsequently, there arises a problem that an abrasion is generated by the friction between the outer circumferential side of the piston reciprocating in the compression space (P) of the cylinder 4 and the inner circumferential side of the cylinder 4.
Therefore, it is an object of the present invention to provide a piston supporting structure for an linear compressor in which a spring elastically supporting a piston supports the piston, being only axially contracted and relaxed by the reciprocating movement of the piston in receipt of driving force of a motor, while not being displaced in a radial direction, thereby preventing an abrasion of the piston and cylinder and increasing the compressing efficiency of the compressor.
In order to achieve the above-described objects of the present invention, there is provided a piston supporting structure for an linear compressor including: a piston reciprocating in the axial direction in receipt of driving force of a motor; a first spring of which one end portion is fixed to one side of the piston; and a second spring of which one end portion is fixed to the other side of the piston.